β-Glucans are involved in immune-modulation of THP-1 macrophages

We aimed to examine different immunological aspects of β-glucans derived from different food sources (oat, barley and shiitake) on phorbol myristate acetate (PMA)-differentiated THP-1 macrophages. Commercially purified barley β-glucan (commercial BG) and lentinan were included to compare β-glucans from the same origin but different degree of purity and processing.

Chemical composition and molecular weight distribution of β-glucan samples were determined. Inflammation-related gene expression kinetics (IL-1β, IL-8, nuclear factor kappa B [NF-κB] and IL-10) after 3, 6 and 24 h of stimulation with 100 μg/mL β-glucan were investigated. All tested β-glucans mildly upregulated the observed inflammation-related genes with differential gene expression patterns. Similar gene expression kinetics, but different fold induction values, was found for the crude β-glucan extracts and their corresponding commercial forms. Pre-incubation of THP-1 macrophages with β-glucans prior to lipopolysaccharide (LPS) exposure decreased the induction of inflammation-related genes compared to LPS treatment. No production of nitric oxide (NO) and hydrogen peroxide (H₂O₂) was detected in β-glucan stimulated THP-1 macrophages. Phagocytic activity was not different after stimulation by β-glucan samples.

Based on these in vitro analyses, it can be concluded that the analysed β-glucans have varying levels of immunomodulating properties, which are likely related to structure, molecular weight and compositional characteristic of β-glucan.